1. Field of the Invention
The present invention relates generally to filtration and more particularly to a fluid filter of the spin-on or throw-away type adapted to be screwed onto a filter mounting means and which is capable of withstanding operational pressures in excess of 1000 psi.
2. Description of the Prior Art
Spin-on or throw-away filters have become regularly accepted in those areas where liquid filtration at relatively low pressures (not exceeding 300 psi) are employed. As a result of this success, a demand has been created in industrial applications wherein surge pressures in excess of 1000 psi can occur. Various attempts have been made to construct spin-on type filters to meet the demands for such highpressure usage. One such attempt is disclosed in U.S. Pat. No. 3,859,216 which incorporates a rigid base plate which is held in position by a cover plate which is secured by a roll seam to the edge of the housing in which the filter is disposed. Another attempt at providing a filter for high-pressure operations is disclosed in U.S. Pat. No. 4,369,113 which also includes a base plate which seals the opening of the housing in which the filter element is disposed. The housing and base plate are secured together by folding the upper periphery of the housing over the top of the base plate and then back upon itself to thus form a folded connection between the base plate and the housing.
Although the filters of the prior art have proven satisfactory under certain limited conditions, it has been found that the housing may deform, allowing leakage around the seals, particularly at high or pulsating high pressure, or alternatively, the folds provided in the housing to accomplish a seal with the base plate may unfold, creating a failure in the filter.